Currently, there are many military and law enforcement situations requiring the disablement of explosive ordnance, for example, disarmament of improvised explosive devices (IED) or modified unexploded ordnance (modified UXO) encountered by military personnel during wartime scenarios or encountered by law enforcement officials in domestic environments. Further there are non-tactical and peacetime activities such as ordnance remediation and demilitarization where UXO are neutralized for safety reasons.
Current counter-IED means include forced detonation as taught by U.S. Pat. No. 7,051,636, Show, et al and U.S. Pat. No. 7,130,624, Jackson, et al; thwarting firing electronics with jammers or decoy signals as taught by U.S. Pat. No. 7,318,368, Ham, et al and U.S. Pat. No. 7,512,511, Schultz, et al; or mechanically breaking apart IED fuse mechanisms as taught by U.S. Pat. No. 6,644,166, Alexander, et al and U.S. Pat. No. 7,481,146, Weiss, et al. Non-tactical neutralization techniques include controlled burning of the explosives as taught by U.S. Pat. No. 7,501,551, Eidelman, et al and U.S. Pat. No. 7,331,268, Pangilinan, et al; contained detonation techniques as taught by U.S. Pat. No. 7,373,867 Ryan, et al; mechanical fuse removal as taught by U.S. Pat. No. 7,328,643, Goetsch, et al; chemical processes to destroy fuses as taught by U.S. Pat. No. 7,073,424, Ferrari, et al and bioremediation processes to disable explosives as taught by U.S. Pat. No. 7,077,044, Badger, et al. There are currently no known means to disable detonators without detonation, mechanical disassembly or physical impact.
Explosive devices are typically based on a bridgewire detonator, or Blasting Cap (BC) originally demonstrated by Dr. Robert Hare in 1832 and later taught by U.S. Pat. No. 991,373, Rennie & Jessen. A blasting cap (BC) is a small sensitive primary explosive device generally used to detonate a larger, more powerful and less sensitive secondary explosive (e.g. C4, dynamite). BCs are designed with specifically defined conditions that result in ignition and resultant primary detonation. Electric BCs typically contain a bridgewire that, when heated by an electric current, causes ignition and subsequent device detonation. The bridgewire is typically soldered between the BC electrodes or leads and has resistive characteristics that result in specific heating correlated to current. The bridgewire is typically dipped in a pyrotechnic, ignition mix or spot charge that has a specific ignition point based on temperature rise, as a function of time, and as a result of resistive heating. This initial controlled ignition sets off subsequent, less sensitive explosives within the BC and subsequently the explosive ordnance. Specific current magnitudes are of primary importance to the functioning of the BC. Specifically the “max no fire current” may be defined as the greatest current that can be applied over a time specified without ignition. The “min all fire current” may be defined as the current that results in 100% ignition of a single detonator within 500 msec.
It has been suspected that certain electromagnetic interference (EMI) radiation has detrimental effects on the performance of bridgewire detonators. EMI bridgewire degradation is a suspected factor with reduced fuse and pyrotechnic reliability of shipboard munitions due to Hazards of Electromagnetic Radiation to Ordnance (HERO) effects, other high electromagnetic (EM) environments (space, battlefield), and as a result of EM qualification testing. While noticed, this factor was little understood. With further investigation we have found this degradation phenomenon to be understandable and reproducible. This investigation faulted the basis for the subject invention.
The invention disclosed herein generally relates to disablement of a blasting cap (BC) of an explosive ordnance. Further, the disclosed invention relates to a method, apparatus and system for disablement of a BC without requiring physical contact, and without imparting physical impact to the target explosive device. In particular, the invention disclosed herein relates to a method, apparatus, and system for disabling a bridgewire initiator of a BC using a power application sequence to raise the resistance of the bridgewire initiator to produce an impractical firing condition for the explosive ordnance.
Current explosive ordnance neutralization systems, also commonly referred to as explosive ordnance disposal (EOD), and may involve a mechanical impact through an aimed projection of mass, e.g., a projectile, whereby the projectile hits the targeted explosive ordnance, breaking the explosive ordnance's firing mechanism prior to a detonation of the explosive ordnance. The mechanical impact explosive ordnance neutralization systems of Alexander and Weiss may create hazardous conditions both for military and law enforcement personnel during disabling of the explosive ordnance and additionally for individuals and facilities located near the explosive ordnance. These hazardous conditions may be created by collateral damage caused by shrapnel or projectiles discharged from the conventional disrupter or when the disrupter projectile hits the explosive ordnance causing the projectile and/or ordnance to break apart upon impact, or by the inadvertent causing of detonation due to mechanical disturbance. In some instances, the mechanical impact may release contaminants or harmful materials, for example, nuclear, biological or chemical contaminants, which may be contained within an explosive terrorist device. Thus, disarmament of explosive ordnance in a densely populated area may need to be handled differently from the disarmament of explosive ordnance in a remote location.
Further, a mechanical impact on the explosive ordnance may destroy evidence, for example, forensic evidence used to determine the materials used to construct the explosive ordnance or to determine the party responsible for laying the explosive ordnance.
Forced detonation techniques, whether contained (Ryan) or not (Show, Jackson) similarly produce the undesirable effects of creating hazardous conditions for personnel and facilities as well as destroying forensic evidence. Jamming and thwarting as taught by Ham and Schultz do not definitively render the detonator and explosive device inoperable. Controlled burning as taught by Eidelman and Pangilinan, mechanical fuse removal as taught by Goetsch, and chemical techniques as taught by Ferrari require physical contact with the device implying personnel hazards. Bioremediation processes as taught by Badger are not conducive to C-IED/EOD applications as they are less structured, time consuming, and do not result in a definitive neutralized state in a process controlled manner.
Current explosive ordnance neutralization systems may also involve robotic devices used to remove the explosive ordnance from a densely populated area for detonation in a remote location. However, such explosive ordnance neutralization systems may still create hazards both to the robotic device transporting the explosive ordnance to the remote location and further to individuals or facilities located within the path of transport of the “live” explosive ordnance. Robotic explosive ordnance neutralization systems may also include infrared jamming, electromagnetic “forced” detonation, or electronic jamming devices; however, none of these robotic systems have demonstrated the ability to degrade and disable a blasting cap's (BC's) bridgewire initiator, rendering the BC inoperable by causing an impractical firing condition for the explosive ordnance.
The disabling/degrading method used by itself results in no outward means to confirm success without performing physical analysis or functional testing of the device. In some applications this lack of confirmation may be acceptable. For others, there is an understandable hesitancy by users (e.g. bomb disposal technicians) to entrust the process. A complimentary polling process that ascertains bridgewire integrity in conjunction with the disabling/degrading process provides this information. There are observable trends in bridgewire parameters that change during the process of bridgewire disabling including current, impedance and temperature. There are existing technologies and methods to measure these parameters. It is the novel implementation and application of these technologies and methods in conjunction with the claimed disabling/degrading method that is claimed for the purpose of polling bridgewires, confirming their performance status, and as a control feedback parameter for the disabling/degrading technique.
Monitoring for such trends provides process status and ultimately confirms process success. The amount of power projected correlates to the power available for coupling into the bridgewire circuit, resulting in current flow through the bridgewire. Further, monitoring bridgewire current/impedance/temperature provides indications as to bridgewire integrity.
What is needed is a method, an apparatus, and a system capable of disarming the explosive ordnance without creating hazardous conditions both for military and law enforcement personnel and robotic devices disarming the explosive ordnance, and additionally for individuals and facilities located near the “live” explosive ordnance.
Further, what is needed is a method, an apparatus, and a system capable of disarming the explosive ordnance without collateral damage to preserve physical evidence used to determine the materials used to construct the explosive ordnance or to determine the party responsible for laying the explosive ordnance, and to prevent the release of contaminants or harmful materials that may be contained within the explosive ordnance.
Therefore, what is needed is a method, an apparatus, and a system capable of remotely disabling the firing mechanism of the explosive ordnance without a physical or mechanical detonation of the explosive ordnance using a power sequence waveform to disable the bridgewire initiator of the explosive ordnance's BC.
Therefore, what is needed is a method, an apparatus, and a system capable of remotely disabling the firing mechanism of the explosive ordnance without direct human or robotic contact or exposure to the explosive ordnance.
Further, what is needed is a method, an apparatus, and a system capable of remotely polling the bridgewire to assess it performance characteristics correlated to the disabling and degrading process.